Medical waste, as generated in medical, veterinary, dental and laboratory facilities, includes a wide variety of materials and substances, including bandages, gloves, infusion bags, hypodermic needles, syringes, products of dialysis, testing vials, plastic bags, tubes, containers, blood, human and animal wastes. Medical waste must be disposed in a safe, expeditious and hazard-free manner. In large medical facilities, the medical waste is generally collected at a central location and treated by incineration or steam disinfection before disposal into a landfill. Such processes are not only costly, but may also be environment-unfriendly in pollution generated during treatment, their reliance upon transportation of the waste to an offsite treatment facility, and in the less-than-optimal use of environmental un-renewable resources.
Because of the different types of medical waste to be disposed, a number of devices have been developed which include shredders for shredding the medical waste in order to reduce the overall volume and to facilitate sterilization or disinfection. U.S. Pat. Nos. 5,620,654 and 6,494,391, the entire content of both being incorporated herein by reference, relate to equipment having a footprint with sufficiently small dimensions facilitating installation in hospital departments or wards, laboratories or clinics for on-site treatment, disinfection, and localized disposal. Such systems relate particularly to a method and equipment for automatically grinding, sanitizing and neutralizing both acid and basic medical waste, and for disposing it after treatment.
The '654 patent discloses equipment mounted in a tightly closable housing provided with charge and discharge openings. The housing contains a shredder for comminuting the inserted raw waste and for conveying the shredded material to a mixing vessel where it is diluted with water and thoroughly mixed. A container storing tubes filled with several kinds of sanitizing materials is configured to dispense the required number and kinds of tubes into the shredder in accordance with the pH value of the mixture. The pH level is communicated to a selective valve mechanism by a sensor attached to the vessel. The equipment further includes a pump for recirculating liquid from the vessel to the shredder, and a pump for draining fluid from the mixing vessel. A conveyor (25) conveys the sanitized waste out of the vessel and out of the housing. Electronic and control equipment is provided for operating the various components.
While the invention described in the '654 patent has been incorporated in commercial settings, such apparatus is relatively large and costly, and therefore has been found to be more suitable for relatively large medical facilities, such as large-size and medium-size hospitals. The '391 patent improves upon the teachings of the '654 patent by providing medical waste treatment equipment suitable to relatively small facilities, such as medical, dental, dialysis and veterinary clinics. To achieve this goal, such equipment includes a treatment vessel having an open top, pivotal within a housing, between a waste-loading position, a waste-treating position and a waste-removing position. In the waste-loading position, the open top of the treatment vessel is aligned with the housing inlet for receiving the waste. In the waste-treating position, the waste is shredded by a shredder unit disposed within the treatment vessel, and in the waste-removing position, the open top of the vessel is aligned with the housing outlet for removing the shredded waste. The apparatus further may additionally include a compactor head for compacting the waste within the treatment vessel, a water feed line, and a disinfectant feed line, for feeding water and a disinfectant into the treatment vessel, and a mixer for mixing with the waste while it is being compacted and shredded.